The efficient production of crops requires that seed planters meet certain primary design objectives which are: creating a furrow having an accurate planting depth and preferably providing soil having a reasonably high moisture content for early germination; accurate seed spacing; and seed to soil contact. This invention is primarily concerned with the furrow forming aspect of a planter.
A known seed planter utilizes a conventional pair of rotatably mounted, generally flat, disk openers that substantially contact each other where the disks enter the ground and diverge apart rearwardly and upwardly. The disks are supported on a frame which is connected to a tool bar of a mobile power source by a parallel support (i.e., parallelogram) linkage so that the frame is maintained in a generally horizontal position parallel to the ground despite varying ground contours. A down-pressure spring arrangement extends between the upper and lower links of the parallel linkage to apply varying amounts of up or down pressure to the linkage and thereby decrease or increase the force applied to the disks to insure that they properly penetrate the soil. The springs, depending on their relative lever arms on the upper and lower links of the linkage, can apply varying amounts of up as well as down pressure.
It has heretofore been the usual practice to provide a pair of spaced apart down-pressure springs having lower ends received by a tube rigidly secured to the lower links, and upper ends received by a channel attached between the upper links. The upper links are provided with longitudinally spaced openings formed therein, and the channel can be selectively positioned along the length of the links by the use of bolts extending through the link openings and which are received by the ends of the channel. In order to reposition the down pressure springs and thereby adjust the up or down pressure of the support linkage, it is necessary to remove the bolts from each end of the channel, reposition the channel adjacent the selected link openings and then re-install the bolts. This is a time-consuming job and many times an operator will neglect to do it on a multi-row planter. This may result in poor performance of the planter.
The present invention solves this problem by providing an arrangement which permits quick and easy adjustment of the aforementioned pressure.